Editing Thames and Severn Canal (section)

===Operation===
Until the summit level was completed, little thought seems to have been given to water supply. It was assumed that the [[River Frome, Stroud|River Frome]], to the west of the tunnel, the [[River Churn]] which flows through [[Cirencester]], and the [[River Coln]], together with springs at [[Boxwell]] and a well near the source of the River Thames at [[Thames Head]], would be sufficient. The original horse pump at Thames Head was replaced by a windmill, but Clowes found that he could not stop the summit [[canal pound|pound]] from leaking. The flow on the River Churn was {{convert|1.7|e6impgal/day|Ml/day}}, whereas the calculated flow at the start of the project had been more than ten times this value. The summit level was losing around {{convert|1.1|e6impgal/day|Ml/day}}, largely because the underlying rock was porous [[limestone]], and it was estimated that around half of the daily requirement could actually be supplied. The wells at Thames Head were extended and a [[Boulton & Watt]] steam engine was installed in 1792 to pump the water into the canal. An extra, shallow lock was built at Boxwell, which allowed the level of the canal to be dropped beyond it, and more water to be taken from Boxwell springs. The new arrangements were adequate, although some of the reason was the failure of traffic to develop to the levels anticipated.<ref name=jane/>{{sfn |Hadfield |1969 |pp=323–324}}

Leakage was affected by [[spring (hydrosphere)|springs]] breaking through the [[clay]] lining of the canal bed. In summer, when the springs receded, water was lost through these holes at a rate greater than the available supply.{{sfn |Household |2009 |p=178}} In one of the attempts to conserve water, the length of the locks was reduced by {{convert|20|ft|m}}, giving them an unusual double-headed appearance.{{sfn |Household |2009 |p=182}} In a further attempt to prevent water loss, at King's Reach, the section immediately east of Sapperton Tunnel, the canal was lined with [[concrete]] rather than [[puddle clay]]. The concrete invert was {{convert|18|in|cm}} thick, and A. Brome Wilson, the canal's engineer, used pipes to feed water from the underlying springs into the canal, but at a level above the waterline.{{sfn |Household |2009 |p=233}}

Neither of the river navigations to which the canal connected were satisfactory. In the west, the situation was remedied in 1827, on completion of the [[Gloucester and Sharpness Canal]]. On the Thames, there had been a proposal for a canal from [[Lechlade]] to [[Abingdon-on-Thames|Abingdon]] in 1784, and for a cut from [[Inglesham]] to [[Buscot]] in 1788, but neither had been built. Some improvements were made to the river after 1786, but the canal company encouraged the building of bypasses. The [[Wilts & Berks Canal]] was one Thames bypass, providing a link to the river at Abingdon, but did not initially connect to the Thames & Severn Canal. Although it was proposed in 1793, it was not opened until 1810, and the [[North Wilts Canal]], which eventually provided the connecting link from [[Latton, Wiltshire|Latton]] to [[Swindon]] for Thames & Severn traffic to bypass the upper river, was not completed until 1819. Even after this, vessels were restricted by the [[Narrowboat|narrow 7ft width]] of the North Wilts, which was considerably smaller than the rest of the link between the Thames and the Severn, limiting income from cargo.<ref name=":0">{{Cite book |last=Household |first=Humphrey |url=https://www.worldcat.org/oclc/1037949345 |title=The Thames & Severn Canal |date=1987 |publisher=Alden Press |isbn=0-86299-446-2 |edition=First paperback |location=Gloucester |oclc=1037949345}}</ref>

Ultimately, most of the Bristol to London trade used the [[Kennet and Avon Canal]] after it opened in 1810, as it provided a much shorter route than the Thames and Severn Canal.{{sfn |Hadfield |1969 |pp=322–324}} Similarly, the Midlands-London traffic that the proprietors had hoped to attract via the Severn found newer routes further east, such as the [[Grand Junction Canal]], considerably more direct.<ref name=":0" /> Thus, the compromise alignment of the Thames & Severn found itself bypassed, with income mainly generated by carriage of [[Forest of Dean Coalfield|Forest of Dean coal]] to places along the canal rather than the balanced trade of long-distance traffic between Thames and Severn that had been anticipated.<ref name=":0" /> Pleasure cruising, meanwhile, was firmly discouraged, with the proprietors setting a punitive toll of £1 per lock for such boats (equivalent to over £120 today).{{sfn |Household |2009 |p=205}}